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(11) | EP 2 893 585 B1 |
| (12) | EUROPEAN PATENT SPECIFICATION |
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REACTANT FLOW CHANNEL CONFIGURATION TO FACILITATE WATER REMOVAL REAKTANZIENFLUSSKANALKONFIGURATION FÜR ERLEICHTERTE WASSERENTFERNUNG CONFIGURATION DE CANAL DE FLUX DE RÉACTANT POUR FACILITER UN RETRAIT D'EAU |
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| Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). |
BACKGROUND
[0001] Fuel cells are useful as sources of electricity. Fuel cells use a known electrochemical reaction for generating electrical energy. Reactants such as hydrogen and oxygen are used in the electrochemical reaction.
[0002] One of the challenges associated with fuel cell operation is managing the presence of water within a fuel cell. So-called flooding conditions can interfere with fuel cell efficiency resulting in poor performance. Additionally, carbon corrosion is possible when water accumulation in a reactant fuel flow channel causes fuel starvation at various locations.
[0003] US2009/0011310A1 describes a fuel cell bipolar plate having channels. Each channel comprises a microgroove. Microgrooves use the capillary force to transport water into the bottom corners of the channel along its length.
[0004] US2009/0023029A1 shows different channel designs within the separator plates. Each channel includes a small or narrow groove where - due to the capillary force - excessive water may be collected. The water collected and retained within the small groove forces additional water to expand, whereas a blockage of the gas passage is suppressed.
[0005] WO2011/112520A1 describes another flow field plate for a fuel cell having different channel designs.
[0006] It is therefore an object of the present invention to provide an alternative fuel cell component allowing for selectively directing water content within a reactant gas channel.
SUMMARY
[0007] This problem is solved by a fuel cell component according to claim 1 of the present invention.
[0008] An exemplary fuel cell component comprises a reactant distribution plate including a plurality of channels configured for facilitating gas reactant flow such that the gas reactant may be used in an electrochemical reaction for generating electricity in a fuel cell. Each of the channels has a length that corresponds to a direction of reactant gas flow along the channel. A width of each channel is generally perpendicular to the length. A depth of each channel is generally perpendicular to the width and the length. At least one of the width or the depth has at least two different dimensions at a single lengthwise location of the channel.
[0009] The different width or depth dimensions establish two channel portions. At least one of the channel portions tends to remain clear of any liquid water so that reactant gas may continue to flow along the length of the channel even when liquid water is present within the channel.
[0010] Various embodiments will become apparent to those skilled in the art from the following detailed description of example embodiments. The drawings that accompany the detailed description can be briefly described as follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011]
Figure 1 is a diagrammatic, perspective illustration of an example fuel cell component having reactant flow channels designed according to an embodiment of this invention.
Figure 2 is a cross-sectional illustration showing selected features of one example embodiment.
Figure 3 is a cross-sectional illustration showing selected features of another example not covered by the invention.
Figure 4 is a cross-sectional illustration showing the example of Figure 3 in another condition.
DETAILED DESCRIPTION
[0012] Figure 1 shows an example fuel cell component. A reactant distribution plate 20 includes a plurality of channels 22 and ribs 24. The channels 22 are configured for facilitating gas reactant flow. It is known how to incorporate a reactant distribution plate into a fuel cell assembly. The example channels 22 are configured to facilitate gas reactant flow such that the gas reactant may be used in an electrochemical reaction for generating electricity in a fuel cell.
[0013] Each of the channels 22 has a length L corresponding to a direction of gas flow through the channel. Each channel 22 includes a width W dimension that is generally perpendicular to the length L. Each channel in this example has at least two different width dimensions. Two width dimensions W1 and W2 are illustrated in Figure 1. Each channel also has a depth dimension that is generally perpendicular to the length and the width. The illustrated example includes at least two different depth dimensions. Depth dimensions D1 and D2 are shown.
[0014] In this example, each channel 22 includes multiple surfaces. A first surface 30 extends between an outside edge of the channel 22 to a second surface 32. The distance between the second surface 32 and the outside edge corresponds to the depth D2. A third surface 34 is parallel to the first surface 30 and perpendicular to the second surface 32. A fourth surface 36 is spaced from the outside edge a distance corresponding to the depth D1.
[0015] Fifth and sixth surfaces 38 and 40 are situated similarly to the second and third surfaces 32 and 34 but on an opposite side of the channel 22. The distance between the surfaces 34 and 38 corresponds to the width W1. A seventh surface 42 extends between the sixth surface 40 and the outside edge of the corresponding side of the channel 22. The distance between the surfaces 30 and 42 corresponds to the width W2.
[0016] The different width dimensions and the different depth dimensions in the illustrated example exist at the same lengthwise location in the channel 22. In other words, taking a cross-section of the gas reactant distribution plate 20 in a direction perpendicular to the length L includes the different width and different depth dimensions. In the illustrated example, there are different width and depth dimensions along the entire length of each channel.
[0017] As can be appreciated from Figure 2 representing the invention, which is a cross-sectional illustration of an example embodiment, the different width dimensions and the different depth dimensions establish two channel portions 44 and 46 along each channel 22. The two channel portions facilitate allowing gas flow along each channel 22 even when liquid water has accumulated in the channel. The configuration of each channel 22 facilitates the liquid water gathering in one of the portions 44 or 46 while the other portion remains at least partially clear of water to permit gas flow through the channel.
[0018] Figure 2 schematically shows liquid water at 50 within one of the channels 22. The different dimensions within the channel and the configuration of the illustrated example facilitates the water 50 tending to collect in the first portion 44 of the channel. The second portion 46 in this example remains clear such that gas may flow through at least the second portion 46 of the channel.
[0019] One feature of the illustrated example is that continued reactant gas flow through the second portion 46 tends to urge the liquid water 50 to be carried out of the channel 22. The illustrated configuration not only allows for a continuous flow of reactant gas through each channel 22 but also facilitates removing liquid water as reactant gas continues to move through the channel.
[0020] In the example of Figure 2, the material of the gas reactant distribution plate is hydrophobic at least along the inside surfaces 30-42 of the channels 22. The two different capillary radii of the illustrated example tend to destabilize water droplets resulting in water accumulation of the type schematically shown at 50 in Figure 2. Such a drop or bubble of liquid water tends to get carried out of the channel by the continued gas reactant flow through the second portion 46 of the channel 22.
[0021] Figures 3 and 4 show another example not covered by the invention in which the material used for making the gas reactant distribution plate 20 is hydrophilic at least along the surfaces 30-42 of the channels 22. The hydrophilic surfaces tend to cause any liquid water present within the channels to cling toward the surfaces. The two different capillary radii established by the dimensions W1, W2, D1 and D2 in this example tend to destabilize the water film. Any liquid water within the channels 22 in the examples of Figures 3 and 4 has a tendency to enter the region with a smaller capillary radius.
[0022] Figure 3 shows liquid water schematically at 52 and 54 within one of the channels. As can be appreciated, a substantial portion of the channel remains open for reactant gas flow through the channel 22. Figure 4 schematically illustrates additional liquid water 56 accumulated within the channel 22. In this example, at least some of the first portion 44 of the channel 22 remains open for gas reactant flow through that channel.
[0023] In some examples not covered by the invention, at least one of the surfaces within the channels 22 is hydrophilic while at least one of the other surfaces is hydrophobic. Such examples allow for selectively directing water content within a channel 22 while realizing the benefit of having different dimensions within the channel for establishing different portions of the channels to handle any liquid water accumulation in a manner that does not prevent reactant gas flow through a channel.
a reactant distribution plate (20) including a plurality of channels (22) configured for facilitating gas reactant flow such that the gas reactant may be used in an electrochemical reaction for generating electricity in a fuel cell, each of the channels (22) having a length (L) that corresponds to a direction of reactant gas flow along the channel (22),
a width (W) perpendicular to the length (L) and a depth (D) perpendicular to the width (W) and the length (L), the width (W) and the depth (D) having at least two different dimensions (W1, W2; D1, D2) at a single lengthwise location,
wherein each channel (22) has a first surface (30) extending from an outside edge of the channel (22) to a second surface (32), the second surface (32) being perpendicular to the first surface (30),
wherein each channel (22) has a third surface (34) extending perpendicular from the second surface (32) to a fourth surface (36), the fourth surface (36) being perpendicular to the third surface (34),
wherein each channel (22) has a fifth surface (38) extending perpendicular from the fourth surface (36) to a sixth surface (40), the sixth surface (40) being perpendicular to the fifth surface (38),
wherein each channel (22) has a seventh surface (42) extending perpendicular from the sixth surface (40) to an outside edge of the channel (22),
wherein the first surface (30), the second surface (34), the sixth surface (40) and the seventh surface (42) establish a rectangular first channel portion (44), and
wherein the third surface (34), the fourth surface (36) and the fifth surface (38) establish a rectangular second channel portion (46),
and wherein the gas reactant distribution plate (20) is hydrophobic at least along the surfaces (30, 32, 34, 36, 38, 40, 42),characterized in that the width (W) and the depth (D) have at least two different dimensions (W1, W2; D1, D2) along the entire length (L) of each channel (22), wherein the dimensions (W1, W2, D1, D2) within the channel (22) facilitate water (50) to collect in the first portion (44) of the channel (22), while keeping the second portion (46) of the channel (22) clear such that gas may flow through at least the second portion (46) of the channel (22).
eine Reaktantenverteilungsplatte (20) mit einer Vielzahl von Kanälen (22), die so konfiguriert sind, dass sie einen Gasreaktantenfluss erleichtern, so dass der Gasreaktant in einer elektrochemischen Reaktion zur Erzeugung von Elektrizität in einer Brennstoffzelle verwendet werden kann, wobei jeder der Kanäle (22) eine Länge (L) aufweist, die einer Richtung des Reaktantengasflusses entlang des Kanals (22) entspricht,
eine Breite (W) senkrecht zur Länge (L) und eine Tiefe (D) senkrecht zur Breite (W) und zur Länge (L), wobei die Breite (W) und die Tiefe (D) mindestens zwei unterschiedliche Abmessungen (W1, W2, D1, D2) an einer einzigen Stelle in Längsrichtung aufweisen,
wobei jeder Kanal (22) eine erste Oberfläche (30) aufweist, die sich von einer Außenkante des Kanals (22) zu einer zweiten Oberfläche (32) erstreckt, wobei die zweite Oberfläche (32) senkrecht zu der ersten Oberfläche (30) ausgerichtet ist,
wobei jeder Kanal (22) eine dritte Fläche (34) aufweist, die sich senkrecht von der zweiten Fläche (32) zu einer vierten Fläche (36) erstreckt, wobei die vierte Fläche (36) senkrecht zu der dritten Fläche (34) ausgerichtet ist,
wobei jeder Kanal (22) eine fünfte Fläche (38) aufweist, die sich senkrecht von der vierten Fläche (36) zu einer sechsten Fläche (40) erstreckt, wobei die sechste Fläche (40) senkrecht zu der fünften Fläche (38) ausgerichtet ist,
wobei jeder Kanal (22) eine siebte Fläche (42) aufweist, die sich senkrecht von der sechsten Fläche (40) zu einer Außenkante des Kanals (22) erstreckt, wobei die erste Fläche (30), die zweite Fläche (34), die sechste Fläche (40) und die siebte Fläche (42) einen rechteckigen ersten Kanalabschnitt (44) bilden, und wobei die dritte Fläche (34), die vierte Fläche (36) und die fünfte Fläche (38) einen rechteckigen zweiten Kanalabschnitt (46) bilden,
und wobei die Reaktantenverteilungsplatte (20) zumindest entlang der Oberflächen (30, 32, 34, 36, 38, 40, 42) hydrophob ist, dadurch gekennzeichnet, dass die Breite (W) und die Tiefe (D) mindestens zwei unterschiedliche Abmessungen (W1, W2, D1, D2) entlang der gesamten Länge (L) jedes Kanals (22) aufweisen, wobei die Abmessungen (W1, W2, D1, D2) innerhalb des Kanals (22) es dem Wasser (50) erleichtern, sich in dem ersten Abschnitt (44) des Kanals (22) zu sammeln, während der zweite Abschnitt (46) des Kanals (22) frei gehalten wird, so dass Gas zumindest durch den zweiten Abschnitt (46) des Kanals (22) strömen kann.
une plaque de distribution de réactif (20) incluant une pluralité de canaux (22) configurés pour faciliter un écoulement de réactif gazeux de telle sorte que le réactif gazeux peut être utilisé dans une réaction électrochimique permettant de générer de l'électricité dans une pile à combustible, chacun des canaux (22) ayant une longueur (L) qui correspond à une direction d'un écoulement de réactif gazeux le long du canal (22),
une largeur (W) perpendiculaire à la longueur (L) et une profondeur (D) perpendiculaire à la largeur (W) et à la longueur (L), la largeur (W) et la profondeur (D) ayant au moins deux dimensions différentes (W1, W2 ; D1, D2) au niveau d'un emplacement unique dans la longueur, dans lequel chaque canal (22) a une première surface (30) s'étendant d'un bord extérieur du canal (22) à une deuxième surface (32), la deuxième surface (32) étant perpendiculaire à la première surface (30),
dans lequel chaque canal (22) a une troisième surface (34) s'étendant perpendiculairement de la deuxième surface (32) à une quatrième surface (36), la quatrième surface (36) étant perpendiculaire à la troisième surface (34),
dans lequel chaque canal (22) a une cinquième surface (38) s'étendant perpendiculairement de la quatrième surface (36) à une sixième surface (40), la sixième surface (40) étant perpendiculaire à la cinquième surface (38),
dans lequel chaque canal (22) a une septième surface (42) s'étendant perpendiculairement de la sixième surface (40) à un bord extérieur du canal (22),
dans lequel la première surface (30), la deuxième surface (32), la sixième surface (40) et la septième surface (42) forment une première partie de canal rectangulaire (44), et
dans lequel la troisième surface (34), la quatrième surface (36) et la cinquième surface (38) forment une seconde partie de canal rectangulaire (46),
et dans lequel la plaque de distribution de réactif gazeux (20) est hydrophobe au moins le long des surfaces (30, 32, 34, 36, 38, 40, 42), caractérisé en ce que
la largeur (W) et la profondeur (D) présentent au moins deux dimensions différentes (W1, W2 ; D1, D2) sur toute la longueur (L) de chaque canal (22),
dans lequel les dimensions (W1, W2, D1, D2) à l'intérieur du canal (22) facilitent la collecte d'eau (50) dans la première partie (44) du canal (22), tout en laissant la seconde partie (46) du canal (22) dégagée de telle sorte qu'un gaz peut s'écouler à travers au moins la seconde partie (46) du canal (22).
REFERENCES CITED IN THE DESCRIPTION
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.
Patent documents cited in the description